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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jul 19, 2015 2:27 pm Post subject: Radio Buzz

At 02:24 PM 7/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Dj Merrill <deej(at)deej.net>



 On 7/19/2015 3:15 PM, Ross Mickey (home) wrote:

 > I have identified that the buzz/static is coming from the new AFS 5600

 > EFIS I just installed.  

 > 

 > Now what do I do?

 	


    A number of appliances with LCD screens

    were notorious radiators. I think the problems

    were centered around the micro-watt dc to ac

    converter used to bias up the screen. I'd not

    heard of any difficulties in years . . . I

    assumed that everyone had figured it out by

    now . . . but apparently not.



    The fact that moving wires made difference 

    suggests that the noises MAY be radiated from

    wire bundles as opposed to from the LCD face.

    Again, the hand-held transceiver can be used

    to 'sniff' around the box . . . much like you

    would use a freon leak detector to find a bad

    joint.  You may want to make a 'special' antenna

    for the hand held that is only an inch or so long

    so that its not terribly efficient . . . 



 

 

   Bob . . .    [quote][b]

rossmickey(at)comcast.net
Guest

Posted: Sun Jul 19, 2015 3:15 pm Post subject: Radio Buzz

I identified it was the EFIS by pulling the fuse. 



Ross Mickey

541-954-7521

 	  Quote: 	
		   On Jul 19, 2015, at 2:10 PM, Kelly McMullen <kellym(at)aviating.com> wrote:

 

 

 

 Turn the EFIS off with circuit breaker. See if the noise goes away. Then call AFS/Dynon for advice if that proves to be the source of the noise.

 

> On 7/19/2015 12:15 PM, Ross Mickey (home) wrote:

> I have identified that the buzz/static is coming from the new AFS 5600 EFIS I just installed. I have lessened the static sound some by re routing some wires. I also now can see that the rear antenna is being slightly affected also. All of the grounds look good going to a common ground block attached to the battery.

> 

> Now what do I do?

> 

> Ross Mickey

> 

> 

> 

>> On Jul 17, 2015, at 12:43 PM, Ross Home <rossmickey(at)comcast.net <mailto:rossmickey(at)comcast.net>> wrote:

>> 

>> Thanks so much, Bob. I will do as you suggest when I get back out to the hangar.

>> 

>> Just for my education.  Since the location of the coax is not an issue, am I to understand that the interference I am experiencing is being picked up by the forward antenna itself?

>> 

>> In surfing the web about comm antenna, I read about the importance of having good electrical bonding of the antenna to the aircraft ground.

>> 

>> The electrical bonding of the antennas to the aircraft skin is best accomplished by direct metal-to metal contact of the antenna base to the aircraft skin. To accomplish this, the aircraft paint in the mounting area will need to be removed and the surface alodined to protect aluminum against corrosion. An alternate method for providing electrical bonding is through the mounting screws, which attach to a backing plate inside the aircraft skin. Remove any interior paint in the area where the backing plate is placed to assure a good ground. Coat this area with alodine to minimize corrosion. To test the electrical bonding of the blade to the aircraft, a reading of .003 ohms between the antenna base plate and ground should be achieved.

>> 

>> I am using the second method and will have to check if my installation meets the .003 ohm test.  If the front antenna does not meet this, would this cause a buzz or just degrade the performance of the antenna?

>> 

>> Ross

>> 

>> *From:*owner-aeroelectric-list-server(at)matronics.com <mailto:owner-aeroelectric-list-server(at)matronics.com> [mailto:owner-aeroelectric-list-server(at)matronics.com] *On Behalf Of *Robert L. Nuckolls, III

>> *Sent:* Friday, July 17, 2015 11:45 AM

>> *To:* aeroelectric-list(at)matronics.com <mailto:aeroelectric-list(at)matronics.com>

>> *Subject:* Re: Radio Buzz

>> 

>> At 11:05 AM 7/17/2015, you wrote:

>> 

>>    Since you have ruled out external sources, it sort of points to

>>    the front antenna cable. I thought you said you had tried

>>    swapping cables.

>>    Try removing antenna from airframe, connecting it directly to

>>    radio and see if there is noise.

>>    I can't explain it, but I know of one case where noise was coming

>>    via ground, and isolating the antenna from ground cured the

>>    problem. Perhaps a ground loop between coax shield and the

>>    airframe ground.

>> 

>>    On 7/17/2015 7:51 AM, Ross Home wrote:

>> 

>>        I will try this.

>> 

>>        What is puzzling is that the antenna connection that leads to

>>        the rear antenna is at the firewall about 18 inches and level

>>        with my GX-60.  I can easily unhook the GX-60 cable from the

>>        front antenna (which is under the floor directly beneath the

>>        GX-60) and hook it to the rear antenna connection which is at

>>        the same height as the GX-60 and the noise goes away.  All of

>>        the wires that the GX-60 cable passes are the same in either

>>        case except, when it is connected to the front antenna, it

>>        crosses these wires at a 90 degree angle instead of running

>>        parallel to them when it goes the rear antenna connection.

>> 

>> 

>>  Routing of coax cables to antennas is NEVER

>>  a component of received noise . . . in the

>>  heavy iron we route coaxes where there is opportunity

>>  and room. The whole idea behind the industry standard

>>  practices for (1) limiting noise from antagonists,

>>  (2) improving resistance to noise by judicious

>>  design of potential victims and last (3) reducing

>>  risk of over-whelming propagation path (mounting

>>  an antenna under the cowl will probably pick up

>>  ignition noise). When a noise coming in through

>>  the receiver's antenna port is detected, placement

>>  of the coax isn't even a distant finisher in the

>>  quest for resolution.

>> 

>>  Assuming you have paid due diligence to standard practices

>>  for installing the two antennas then the fact that

>>  the forward-most antenna seems to be the key propagation

>>  port, then the noise source is most likely forward ON

>>  the aircraft. If it were off the aircraft, both

>>  antennas would hear it.

>> 

>>  This problem has a lot in common with Col_Mustard-

>>  did-it-in-the-library-with-a-rope . . . you gotta

>>  gather all the clues available to you BEFORE picking

>>  up hammers-n-saws . . . or screwdrivers.

>> 

>>  Antennas don't go BAD in a manner that makes one

>>  a source of noise while others are not. They either

>>  work good . . . or they don't . . . but they're never

>>  'noisy'. Start with a 'cold' panel and bring up

>>  equipment one item at a time . . . then confirm

>>  your preliminary findings with a sniffer receiver.

>> 

>>  Only THEN will hammers, saws and screwdrivers

>>  contribute to resolution of the problem.

>> 

>> 

>>  Bob . . .

>> 

>> **

>> **

>> **

>> **

>> **

>> **

>> **

>> **http://www.matronics.com/Navigator?AeroElectric-List****

>> ****

>> ****

>> ***http://forums.matronics.com*****

>> ******

>> ******

>> ******

>> ******

>> ****http://www.matronics.com/contribution******

>> ******

>> ******

>> **

>> *D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D lectric-List"">http://www.matronics.com/Navigator?AeroElectric-List D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D //forums.matronics.com D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D ot;">http://www.matronics.com/contribution D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D *

>> **

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rossmickey(at)comcast.net
Guest

Posted: Sun Jul 19, 2015 3:17 pm Post subject: Radio Buzz

I will try to rig a short antenna. As it is, I get about 6-9 inches from the EFIS to set off the sniffer (a handheld radio)



Ross Mickey

541-954-7521





On Jul 19, 2015, at 3:22 PM, Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

[quote]  At 02:24 PM 7/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Dj Merrill <deej(at)deej.net (deej(at)deej.net)>



 On 7/19/2015 3:15 PM, Ross Mickey (home) wrote:

 > I have identified that the buzz/static is coming from the new AFS 5600

 > EFIS I just installed.  

 > 

 > Now what do I do?

 	


    A number of appliances with LCD screens

    were notorious radiators. I think the problems

    were centered around the micro-watt dc to ac

    converter used to bias up the screen. I'd not

    heard of any difficulties in years . . . I

    assumed that everyone had figured it out by

    now . . . but apparently not.



    The fact that moving wires made difference 

    suggests that the noises MAY be radiated from

    wire bundles as opposed to from the LCD face.

    Again, the hand-held transceiver can be used

    to 'sniff' around the box . . . much like you

    would use a freon leak detector to find a bad

    joint.  You may want to make a 'special' antenna

    for the hand held that is only an inch or so long

    so that its not terribly efficient . . . 



 

 

   Bob . . .     	  Quote: 	
		  

	


[b]

rossmickey(at)comcast.net
Guest

Posted: Sun Jul 19, 2015 3:19 pm Post subject: Radio Buzz

Everything wired as shown in diagrams. My antenna on my handheld is to good so I can't differentiate wires. 



Ross Mickey

541-954-7521

 	  Quote: 	
		   On Jul 19, 2015, at 3:06 PM, user9253 <fransew(at)gmail.com> wrote:

 

 

 

 Is the AFS 5600 EFIS wired according to the installation manual?  Usually shielded cables are grounded at the source end only, but not always.  Can you identify one or more wires from the AFS 5600 EFIS that are causing the noise?

  Is the squelch on the com radio adjusted too sensitive?

 Joe

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=444951#444951

ceengland7(at)gmail.com
Guest

Posted: Sun Jul 19, 2015 3:46 pm Post subject: Radio Buzz

Try it with no antenna at all. If you don't get any noise that way, just 

stick a short piece of safety wire into the center of the antenna 

connector & try that. (Don't transmit.  )

On 7/19/2015 6:18 PM, Ross Mickey (home) wrote:

 	  Quote: 	

 Everything wired as shown in diagrams. My antenna on my handheld is to good so I can't differentiate wires.

 Ross Mickey

 541-954-7521

> On Jul 19, 2015, at 3:06 PM, user9253 <fransew(at)gmail.com> wrote:

>

> 

>

> Is the AFS 5600 EFIS wired according to the installation manual?  Usually shielded cables are grounded at the source end only, but not always.  Can you identify one or more wires from the AFS 5600 EFIS that are causing the noise?

>   Is the squelch on the com radio adjusted too sensitive?

> Joe

>

> --------

> Joe Gores

>

user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Sun Jul 19, 2015 5:00 pm Post subject: Re: Radio Buzz

If I dim my Dynon D-180 screen, it makes noise in the headset.  I leave the screen on full bright (never fly at night) and the noise is not noticeable.

Joe



 	  Quote: 	
		  A number of appliances with LCD screens 

were notorious radiators. I think the problems 

were centered around the micro-watt dc to ac 

converter used to bias up the screen. I'd not 

heard of any difficulties in years . . . I 

assumed that everyone had figured it out by 

now . . . but apparently not.

_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2015 5:10 am Post subject: Radio Buzz

At 05:06 PM 7/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 Is the AFS 5600 EFIS wired according to the installation manual?  Usually shielded cables are grounded at the source end only, but not always.  Can you identify one or more wires from the AFS 5600 EFIS that are causing the noise?

   Is the squelch on the com radio adjusted too sensitive? 	


   As a general rule, no appliance slated to use

   in airplanes should require ANY special attention

   on the part of the installer to mitigate a noise

   issue.  The qualification testing for TC aircraft

   puts your black box out on a copper-top table, wires

   it up to function stand-alone with no less than 2 meters

   of "ship's wiring" and it should be neither sensitive

   to or an emitter of unfriendly energy sources.



   If any manufacturer suggests 'adding filters, moving

   wires, adjusting antenna locations, etc. . . they

   are admitting to their lack of due diligence in

   design/fabrication of their product.



 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2015 5:13 am Post subject: Radio Buzz

At 06:16 PM 7/19/2015, you wrote:

  	  Quote: 	
		  I will try to rig a short antenna. As it is, I get about 6-9 inches from the EFIS to set off the sniffer (a handheld radio)



 Ross Mickey 	


   Your zeroing in on the root cause . . . I have

   an h-t antenna that's only about an inch long with

   a 1/2" disk soldered to the end. This can be used

   to probe wires, openings in enclosures, lcd screens,

   etc.



   Of course, this only works with noise sources that have

   strong amplitude modulated components . . . but if you

   can 'hear' it in your nav-comm, you can generally 'sniff

   it' with a hand-held.



 

 

   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2015 5:14 am Post subject: Radio Buzz

At 08:00 PM 7/19/2015, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>



 If I dim my Dynon D-180 screen, it makes noise in the headset.  I leave the screen on full bright (never fly at night) and the noise is not noticeable.

 Joe

 	


  Unfortunately, all too common . . .



 

 

   Bob . . .    [quote][b]

rossmickey(at)comcast.net
Guest

Posted: Mon Jul 20, 2015 8:15 am Post subject: Radio Buzz

With my dumbed down handheld sniffer I have identified the major culprit and perhaps a second.  The main interference (80%-90%) is from an 18” piece of unused OAT wire that is plugged into the main harness with pos, signal and shield all pinned in the harness.  In talking with AFS tech support, the three options are, 1) connect the pos and signal wires together 2) connect the signal and shield together or 3) unpin all three wires from the harness and remove the whole thing.

 

The second culprit is a couple of the serial port wires (2 of the 4).  These are emanating some interference which is probably caused by my error.  I connected a black the wire coming out of the premade harness (which is connected to the four shield wires for the serial ports) to ground rather than to the chassis of the EFIS.  The new harnesses from AFS (mine is two years old) do not have this but take care of connecting the serial shields to the chassis in the pinning of the harness.

 

I will check these out on Weds when I get back to the hangar.

 

Thank you all for your help.

 

Ross

 

From: owner-aeroelectric-list-server(at)matronics.com [mailto:owner-aeroelectric-list-server(at)matronics.com] On Behalf Of Robert L. Nuckolls, III

Sent: Monday, July 20, 2015 6:12 AM

To: aeroelectric-list(at)matronics.com

Subject: Re: Radio Buzz

 

At 06:16 PM 7/19/2015, you wrote:



 	  Quote: 	
		  

I will try to rig a short antenna. As it is, I get about 6-9 inches from the EFIS to set off the sniffer (a handheld radio)



Ross Mickey 	




  Your zeroing in on the root cause . . . I have

  an h-t antenna that's only about an inch long with

  a 1/2" disk soldered to the end. This can be used

  to probe wires, openings in enclosures, lcd screens,

  etc.



  Of course, this only works with noise sources that have

  strong amplitude modulated components . . . but if you

  can 'hear' it in your nav-comm, you can generally 'sniff

  it' with a hand-held.





  Bob . . .  	  Quote: 	
		    [b]http://www.matronics.com/Navigator?AeroElectric-List 	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
2 	  Quote: 	
		   	
3 	  Quote: 	
		   	
4 	  Quote: 	
		   	
5 	  Quote: 	
		   	
6 	  Quote: 	
		   	
7

  [quote][b]

raymondj(at)frontiernet.n
Guest

Posted: Mon Jul 20, 2015 10:46 am Post subject: Radio Buzz

Does the disk make the the "detector" directionally sensitive, like I'm 

guessing a loop would?



Raymond Julian

Kettle River, MN



The things we admire in men, kindness and generosity, openness, honesty, 

understanding and feeling are the concomitants of failure in our system. 

And those traits we detest, sharpness, greed, acquisitiveness, meanness, 

egotism and self-interest are the traits of success. And while men 

admire the quality of the first they love the produce of the second. 

-John Steinbeck, novelist, Nobel laureate (1902-1968)



On 07/20/2015 08:12 AM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   At 06:16 PM 7/19/2015, you wrote:

> I will try to rig a short antenna. As it is, I get about 6-9 inches

> from the EFIS to set off the sniffer (a handheld radio)

>

> Ross Mickey



    Your zeroing in on the root cause . . . I have

    an h-t antenna that's only about an inch long with

    a 1/2" disk soldered to the end. This can be used

    to probe wires, openings in enclosures, lcd screens,

    etc.



    Of course, this only works with noise sources that have

    strong amplitude modulated components . . . but if you

    can 'hear' it in your nav-comm, you can generally 'sniff

    it' with a hand-held.

    Bob . . .



 *

 *

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Jul 20, 2015 11:26 am Post subject: Radio Buzz

At 11:14 AM 7/20/2015, you wrote:

 With my dumbed down handheld sniffer I have identified the major culprit and perhaps a second.  The main interference (80%-90%) is from an 18” piece of unused OAT wire that is plugged into the main harness with pos, signal and shield all pinned in the harness.  In talking with AFS tech support, the three options are, 1) connect the pos and signal wires together 2) connect the signal and shield together or 3) unpin all three wires from the harness and remove the whole thing.



   I would vote for removing any unused wires

   from the connector.



  

 The second culprit is a couple of the serial port wires (2 of the 4).  These are emanating some interference which is probably caused by my error.  I connected a black the wire coming out of the premade harness (which is connected to the four shield wires for the serial ports) to ground rather than to the chassis of the EFIS.  The new harnesses from AFS (mine is two years old) do not have this but take care of connecting the serial shields to the chassis in the pinning of the harness.



    Hmmmm . . . there's no good reason for serial

    wires to radiate. Single wire data at the

    higher speeds (20-100 kBits/sec) were subject

    to some electro-static coupling issues but

    the designers of RS232 transmitters offered

    connections for a capacitor to slow the transition

    edges of the data.  Twisted pair data architectures

    eliminated this risk.



    I'm disappointed that the EFIS designers didn't

    do a better job of managing this but yes, at

    VHF, the long pig-tail on the shield ground could

    add enough impedance to allow those pesky edges

    to couple out. This may well be an instance where

    the long pigtail not only added the series impedance,

    it became the VHF friendly radiator for the noise.

  

 I will check these out on Weds when I get back to the hangar.



 

    Let us know what you discover . . . be sure to

    let the supplier know too . . . they MIGHT see

    fit to fix this at the next upgrade opportunity.



 

   Bob . . .    [quote][b]

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